Flexible metal band for drum bake ovens



Aug 23 1966 F. THM-:LE ETAL 3,267,877

FLEXIBLE METAL BAND FOR DRUM BAKE OVENS Filed April 5, 1962 4 Sheets-Sheet 1 Fig. 2 3 /9 l2 w v y wW/// l L Aug. 23, 1966 F, THIELE ETAL 3,267,377

FLEXIBLE METAL BAND FOR DRUM BAKE OVENS Filed April 5, 1962 4 Sheets-Sheet 2 Fllg. 4

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FLEXIBLE METAL BAND FOR DRUM BAKE OVENS Filed April 5, 1962 4 Sheets-Sheet 4 United States Patent O 3,267,S77 FLEXIBLE METAL BAND EUR DRUM BAKE OWENS Friedrich Thiele, Walter-FleX-Strasse 3, Hannover, Germany, and Ferdinand Kovac, deceased, late of Linz (Danube), Austria, by Wolfgang Kovac, heir, and Alexandra Kovac, guardian of minor heir, Steingasse 17, Linz (Danube), Austria Filed Apr. 3, 1962, Ser. No. 185,773 4 Claims. (Cl. 11W-5S) The present invention relates to a flexible metal band, such as fordrum baking machines, and in particular for the manufacture of watlle bands.

Drum ovens or baking machines have the substantial advantage over baking machines of other construction thaty continuous waflle bands or the like can be provided in a relatively small space, and that by the .provision of several baking machines, one beh-ind the other, several such bands can be formed from which iilled waffles can be continuously obtained.

Since in such drum baking machines, the metal band forming one side of the baking channel must be returned to the charging side after removal from the drum at the removal side, in which connection it is necessary to conduct the band over reversing rollers or the like, the band is curved once in accordance with the circumference of the drum and at the other time in the opposite direction. Due to the alternating bending stress resulting therefrom, it was attempted at rst to use completely smooth bands. It was found, however, that the production of, for instance, wale baking strips in drum baking machines is not possible with the use of such metal bands, since the dough present in the baking channel is not s-uiliciently anchored and is thus forced sideward by the steam produced in the baking zone, and then forced to a larger extent out of the baking channel in a direction opposite the direction of travel. A non-uniform baked product thus results.

Furthermore, it is not possible with Wafe bands w-hich are produced with smooth metal bands to produce filled baked larticles since the filling layer present between the watlle bands, .and which consists of fat and sugar masses, adheres only to waflle surfaces which have a patterning but not to completely smooth surfaces.

It has now been found in accordance with the invention that truly excellent waffle b-ands or the like can be produced with drum baking machines if the metal band is provided on its one surface with depressions or elevations which 4are of elongated shape and are arranged spaced apart from each other, staggered in transverse rows and vadjacent transverse rows.

In this way, the result is first of all obtained that the dough is anchored in the depressions or by the elevations so that the dou-gh is not forced `out as when using smooth watile bands. ment of the depressions, there remain between them on the surface of the bands channels .along which the steam can pass, On the `other hand, due to the elongated development of the depressions or elevations transverse to the direction of travel of the metal band, an emergence of steam and dough in the direction opposite-to the dir' rection of travel is subjected to considerable resistance. Due to the fact that the elongated depressions are staggered with respect to each other in transverse rows, obliquely extending channels are furthermore formed which, due to the fact that they are interrupted by the depressions, they tend to produce a certain turbulence of the steam flows `and thereby provide additional resistance to such flows. With metal bands provided with depressions or elevations in this manner, it becomes possible therefore for the rst time to produce uni-v Furthermore, with this arrange- ICC formly completely baked waille bands or the like without substantial waste in dr-um baking machines.

Itis particularly advantageous to provide depressions or elevations which are located transversely to the direction of travel since in this way particularly good mechanical properties are obtained, and the bands laccordingly can withstand the strong stresses to which they are exposed in drum baking machines.

The mechanical properties of these bands can, however, be still further improved in accordance with the present invention in the manner that there are provided strips continuous in the direction of travel of the band, which are narrow as compared with the length of the depressions and are free of such depressions, these strips serving as the pulling areas which take up the tensile forces. These strips, in view of their slig-ht Width, are not disturbing from a standpoint of baking technique.

It lhas furthermore proved advantageous to produce the depressions by embossing and to impart to the embossings in longitudinal and transverse cross-section a trapezoida-l form since in this way the outer surface of the band is not damaged.

However, one can also advantageously provide the metal band with diamond-shaped elevations or depressions, in which connection it is also advantageous in order to impr-ove the mechanical properties of the band, to arrange these diamond-shaped depressions or elevations transverse to the direction of travel of the band.

Diamond-shaped elevations facing the material being baked can advantageously be produced by intersecting grooves or Igroove-shaped embossings. It is particularly advantageous in this connection to arrange these embossings at an angle of about 60 to the outer edge of the band.

As described in detail above, it is necessary, particularly in the case of dough which contains a lot of water, and therefore Ifor instance waffle doughs, to remove the steam developed during the baking from the molds. This is effected in accordance with the invention primarily by the outwardly extending smooth paths on the surface of the band, which are formed by the longitudinal depressions or elevations. In order to assist in the removal of the steam, one can provide laterally on the molds small openings or grooves from which the steam can escapel However, it has been found that the steam produced, particularly in the case of a large width of the wall, can only be sufficiently removed in -this manner if the baking times are excessively lengthened and that in case of rapid work, a product which is baked nonuniformly Within the width of the baked strand product is easily produced.

The speed with which the evaporation of water takes place is controlling Ifor the time required for the material to be baked thoroughly. A metal band, in View of its slight thickness, does not have a high heat capacity, and for this reason the evaporation takes place rather slowly in such drum ovens, since only a part of the resultant steam can be removed from the boiling-out grooves provided in known manner on the edge of the drum. An increase of the size of these emergence channels is, however, not possible since this would result in too much of the material to be baked being carried out of said openings, together with the emerging steam.

A substantially faster removal of the steam from the baking material in the case of drum-baking machines is obtained in accordance with the present invention in the manner that the flexbile metal band is provided with boreholes. The boreholes may advantageously in this connection be countersunk on the outside, .and it has proven advantageous to arrange the boreholes substantially in the central zone of the metal band. In this connection, the diameter `of the boreholes is advantageously not greater than the thickness 'of the metal band.

If the boreholes are arranged over the entire width of the metal band, the diameter of the boreholes is advisedly made smaller in the marginal zones Iof the band than those in the central zone and/or the number of boreholes reduced in the marginal zones. It is 'also possible to have the diameter of the boreholes decrease gradually toward the edge of the band.

The speed of baking can be considerably increased by the present invention. Another advantage of the :apparatus in accordance with the invention is ,a reduction in the amount of heat which must be produced for the heating of the metal band and of the drum. It has been found that the structure of the baked material, when using the Iapparatus in accordance with the invention, is also substantially more uniform than in the known embodiments of ovens.

The number and arrangement of the boreholes depends lon the water content of the material to be baked. In this connection it has been found that the maximum borehole diameter of the holes should not be greater than the thickness of the metal band, since otherwise too much of the material to be baked is forced out of the holes. In practice, a ratio of D(the thickness of the bond):s(the diameter of the boreholes)=0.5 is very favorable for wet doughs, such as waffle doughs.

The boreholes for the most part, clean themselves since the adherence of the material in the boreholes is only slight. For better removal of lany material possibly remaining in the boreholes, the boreholes are coun-tersunk on the outside as already pointed out.

The band in yaccordance with the invention can also be used for purposes other than baking, namely wherever flexible metal bands vare used, and it is particularly advantageous that patternings be produced by such .a met-al band.

As material for the metal band, Nirosta steel, beryllium bronze, and the so-called Monel alloy have proven particularly suitable.

Various embodiments of the flexible metal band in accordance with the invention are shown by way of illustration in the drawings in which:

FIG. 1 is -a schematic side View of a drum oven.

FIG. 2 is a section along the line A-B of FIG. l on a larger scale.

FIG. `3 shows -a portion oi the metal band in accordance with a first embodiment of the invention.

FIG. 4 is a top view of an -embossing in accordance with FIG. 3, shown on a larger scale.

FIG. 5 is a section through an embossing in accordance with FIG. 4, along the line A-B.

FIG. 6 is a section through an embossing in accordance with FIG. 4, along the line C-D.

FIG. 7 shows a portion of a band in accordance with the invention having in part groove-shaped embossings.

FIG. 8 is a top view on a larger scale of the finished band in accordance with FIG. 7.

FIG. 9 is a section through the band of FIG. 8, 4along the line E-F.

FIG. l0 is a top View of `a portion of the band in accordance with the invention with boreholes in the band, which boreholes are shown ion a considerably enlarged scale as compared with the width of the band.

FIG. 1l is a partial section through the band of FIG. 10 along the line G-H.

Around a baking'drum 1 Ion the periphery of which a groove 2 is provided to form the baking channel, there is placed an endless metal band 3 which is passed over the reversing drums 4, 5, 6, 7. One of -these drums serves to drive band 3 and thereby drive drum 1. At 8 the dough is sprayed by means of nozzles onto the base of the groove or trough 2 and the baking channel formed thereon is heated on the inside and outside by gas burners 9.

Any baking material 12 which possibly still adheres to the outside of the band is burned by the burners and brushed off by ya rotating steel brush and conveyed via a deector plate 13 into a collecting container.

The metal band 3 is provided in accordance with a first embodiment with the elongated embossings 2a, the detailed shape of which can be noted from FIGS. 3 to 6. 10 are the pulling fields designated by dashed lines, which are free Iof embossings. The arrow 44 indicates the direction 'of travel of the band.

The dimensions of the embossings are, for instance as follows:

Mm. Length 10 Width 1.6 Depth 0.4 Thickness of band 0.5 Distance apart of the rows of embossings 6 Width of the pulling fields 2 FIGS. 7, 8 and 9 show the production of a diamond shaped pattern on the band 3. This can be produced in simple manner by embossing, hammering or the like groove-shaped grooves 15, 16 into the band at approximately an angle of 60 to the outer edge 'of the band. There is then produced a diamond-shaped pattern corresponding to the part of FIGS. 7 and 8 marked 17. In the present case, the individual diamonds 17 form elevations which face the baking material. One c-an, however, also, of course, produce diamond-shaped depressions corresponding to the depressions shown in FIGS. 3 to 6. Furthermore, the depressions may be made deeper than shown in FIG. 9 so that the one side of the band has depressions while the other has elevations.

In accordance with a third embodiment of the invention, the metal band can be provided with boreholes 19, particularly in its center. These boreholes are countersunk toward 4the outside as shown at 20 in FIG. 11 and have a diameter less than the thickness of band 3. They are shown in FIG. l0 applied through band 3, but the band itself as illustrated in FIG. l0 does not show the grooves shown in FIGS. 7 and 8.

We claim:

1. A flexible metal band 4for use in a drum oven comprising, a relatively thin metal band having a plurality of diamond-shaped raised elevations 'on one of its faces, said elev-ations being spaced to provide angularly-extending well-defined grooves between them, the grooves extending diagonally across the band and terminating inwardly of the side edges of the band, the band being provided with a plurality of bore holes extending through it from one face of the band to its opposite face, each bore hole having a diameter not greater than the thickness of the metal band, the bore holes being arranged in a central zone of the band and being countersunk on the outer yface of the band.

2. A flexible metal band forming one side of an oven baking channel, said band having steam-escape holes extending through it from one face `of the band to its opposite face, characterized by the fact that the holes are countersunk on the outer face of the band and the diameter of each hole is not greater than the thickness of the metal band.

3. A flexible metal band `for use in .a drum oven as provided for in claim 2 and wherein the bore holes are arranged only in the central portion of the band.

4. A liexible metal band for use in a drum oven comprising, a relatively thin metal band provided with a plurality of spaced-apart grooves in one of its faces, said grooves extending angularly and transversely across a face of said band, one set of such grooves intersecting the grooves of a second set, whereby raised diamondshaped elevations are provided on one face of the band between the grooves, said band being provided with a plurality of boreholes for steam-escape, said holes 5 6 extending from one face of the band to its opposite FOREIGN PATENTS face. 933 201 9/1955 G rm References Cited by the Examiner i816 10/1906 Geatasrfitain.

UNITED STATES PATENTS 1,300,390 4/1919 Hempel 10/58 5 WALTER A. SCHEEL, Primary Examiner. 2,029,635 2/1936 MSO, 2431 CHARLES A. W1LLMUTH, WILLIAM B. PENN,

Neutehngs et al.

X E Examiners 2,678,614 5/1954 Bahlsen 107--57 3,064,59() 11/ 1962 Thiele 107-57 JOSEPH SHEA, Assistant Examiner. 

4. A FLEXIBLE METAL BAND FOR USE IN A DRUM OVEN COMPRISING, A RELATIVELY THIN METAL BAND PROVIDED WITH A PLURALITY OF SPACED-APART GROOVES IN ONE OF ITS FACES, SAID GROOVES EXTENDING ANGULARLY AND TRANSVERSELY ACROSS A FACE OF SAID BAND, ONE SET OF SUCH GROOVES INTERSECTING THE GROOVES OF A SECOND SET, WHEREBY RAISED DIAMONDSHAPED ELEVATIONS ARE PROVIDED ON ONE FACE OF THE BAND BETWEEN THE GROOVES, SAID BAND BEING PROVIDED WITH A PLURALITY OF BOREHOLES FOR STEAM-ESCAPE, SAID HOLES EXTENDING FROM ONE FACE OF THE BAND TO ITS OPPOSITE FACE. 